<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>交集选择器</title>
    <!-- 既又得关系,即是 p 标签,又是 box 类标签 -->
     <style>
        p.box{
            color: red;
        }
     </style>
</head>
<body>
    <p class="box">p标签,使用了类选择器</p>
    <p>p标签</p>
    <div class="box">div标签,使用了类选择器</div>
</body>
</html>